The reaction of an olefin with hydrogen and carbon monoxide to produce alcohols is the well known hydroformylation/reduction reaction also known as the oxo reaction. When using homogeneous catalysis with metal containing catalysts, soluble in the liquid reaction mixture during the hydroformylation/reduction reaction, there is a necessary recovery and regeneration cost for the dissolved metal catalyst due to the expense of the metal itself and the need to minimize the loss of such metal. Even with sophisticated recovery methods small losses of metal still occur, thus the economic use of homogeneous catalysis using a metal containing catalyst is limited.
Heterogeneous catalysis can be used in the oxo reaction by deploying a catalyst containing transition metal complexes supported upon solid polymers or resins. However, the problem with metal leaching from the solid supported catalyst is still a major consideration due to the cost of recovery or replacement of the catalyst. This metal leaching occurs because some species in the oxo process are better ligands, forming a stronger bond with the metal complex than the ligand functionality of the solid support. A growing recognition of the problem of metal loss due to solubility and leaching from the catalyst is demonstrated by the following prior art. Pruett et al, Journal of Organic Chemistry, Volume 34, page 327, (February, 1969) teaches a catalyst composed of a transition metal complex supported on a solid support, but the complex is soluble in the liquid reaction mixture. U.S. Pat. No. 3,352,924 discloses use of a crystalline alumino-silicate as a solid support for the catalyst, but this catalyst tends to lose effectiveness over time in a continuous operation. U.S. Pat. No. 3,487,112 has disclosed use of transition metal complexes deposited on inert solids, but again the complexes are soluble in the liquid reaction mixture. Haag et al, U.S. Pat. No. 4,098,727 teaches use of a polymer as a solid support for transition metal complexes which then are insoluble in the liquid reaction mixture, due to strong chemical bonds between the polymer and the metal complex. However, in the presence of competing liquid species in the process, the metal complex may be exchanged from the polymer bond to the competing species thus becoming soluble in the liquid reaction mixture. Garrou et al, U.S. Pat. No. 4,262,147 and Hartwell et al, U.S. Pat. No. 4,144,191 discuss applications of transition metal complexes supported by polymers, but do not address the problem of metal leaching from the catalyst.
One aspect of the discovery of the present invention is that control of the species concentration in the oxo process which species is a competing ligand with the catalyst solid support for the metal complex enables this invention to reduce metal leach. In addition, the present invention discloses that when ligand species present invention discloses that when ligand species concentration is favorable, metal leach is further controlled by use of a continuous stirred tank reactor or recirculation reactor as opposed to a single-pass fixed bed reactor. This invention is a process continuously run in such a way as to control metal leach from reactors loaded with a catalyst wherein the transition metal complex catalyst is bound to a solid polymer or resin support. These and other features will become more readily apparent on review of the disclosure described below.